Benzyl methacrylate (BzMA, Aldrich) was deinhibited by passing through a column of basic alumina.Oligo(ethylene glycol) methyl ether methacrylate (OEGMA) (M n = 300 g mol -1 ) (Sigma-Aldrich) was used as received. 2,2'-azobis(isobutyronitrile) (AIBN, Fluka, 98%) was purified by recrystallization from methanol. 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid (CDTPA, Boron Molecular) was used as received. All other reagents were used as received unless otherwise specified.

Poly(stearyl methacrylate) (PSMA) homopolymers, prepared by RAFT radical polymerization, have been employed in the RAFT dispersion polymerization (RAFTDP) of 3-phenylpropyl methacrylate (PPMA) in n-tetradecane. RAFTDPs yielded block copolymers with narrow molecular weight distributions and tunable compositions and allowed for ready access to different polymorphic nanoparticle phases. Polymerization of PPMA at 20 wt %, for a fixed PSMA average degree of polymerization (X̅ n ) of 19, allowed for the in situ preparation of soft matter nano-objects with spherical, worm, and vesicular morphologies. For a fixed block copolymer composition increasing total solids (from 10 to 40 wt %) favored the formation of nanoparticles with higher ordered morphologies. For block copolymer samples that formed soft physical gels at ambient temperature, a macroscopic thermoreversible degelation−gelation phenomenon was observed. The fundamental reason for this was a worm-to-sphere morphology transition that was facilitated, in part, by the low glass transition temperature of the core-forming PPPMA block and an associated increase in the solvation of the core with increasing temperature. Finally, we note that degelation can also be effected by simple dilution with this macroscopic change now due to simple worm disentanglement and not a fundamental morphology transition. ■ INTRODUCTIONThe ability of block copolymers to undergo self-directed assembly in a selective solvent is well documented. 1 Assembly occurs to give soft matter nanoparticles with, most commonly, a spherical morphology although higher ordered; more complex structures are also accessible. 2−14 Traditionally, such selfassembled species are prepared by first synthesizing a welldefined block copolymer (most commonly, but not limited to, an AB diblock species) which, after characterization, is subjected to a processing step to give the nanoparticles. This may involve direct dissolution in a selective solvent or may require additional steps such as gradual stepwise dialysis against a selective solvent from a molecularly dissolved state. While these are well established and perfectly valid approaches to accessing polymeric nanoparticles, this is typically accomplished in dilute solution (≤1 wt % is common), and nano-objects other than spheres can be difficult to obtain.Reversible addition−fragmentation chain transfer dispersion polymerization (RAFTDP) 15−18 has recently been the topic of significant academic interest since it allows for the direct in situ preparation of self-assembled polymeric species of various morphologies (spheres, worms, and vesicles as the most common species) at high concentration (formulations at ≥ 50 wt % are readily achievable) in a one-pot process. The ease of execution and potential versatility of this technique have enabled the syntheses of a wide range of interesting nanoparticles in polar 19−32 (typically aqueous or alcoholic solvents), nonpolar, 33−36 and other, less common, media such as supercritical CO 2 . 37,38 Indeed, RAFTDP is now sufficient...

Poly(stearyl methacrylate) with average degrees of polymerization ranging from 18–30 were prepared by RAFT radical polymerization and then employed as macro-chain transfer agents in RAFT dispersion formulations with 3-phenylpropyl methacrylate as the comonomer.

Well-defined stimulus-responsive polymer gels were prepared from poly(2-vinyl-4,4dimethylazlatone) (PVDMA) via one-pot post-polymerization modification. VDMA homopolymers were reacted with diamine crosslinking agents and functional 1°or 2°amines to form polymer gels that swelled in organic solvents and, in many cases, aqueous solutions. A series of functional amine reagents, including N,N-dimethylethylenediamine (DMEDA), N,N-diethylethylenediamine (DEEDA), morpholine, 3-morpholinopropylamine (MPPA) and tetrahydrofurfurylamine (THFA), were chosen as functional amines to produce polymer gels containing environmentally sensitive species. 13 C solid-state NMR and FTIR spectroscopic measurements confirmed complete conversion of the reactive scaffolds. pH-dependent swelling behavior at ambient temperature was observed in DMEDA-, DEE-DA-and MPPA-modified hydrogels. Kinetic studies showed the swelling behaviors of DME-DA-modified hydrogels were regulated by cross-linker type and concentration in acidic water (pH = 4) at ambient temperature. The swelling ratio of hydrogels modified by DEE-DA, MPPA and THFA also depended strongly on temperature, indicating successful synthesis of thermoresponsive gels. Furthermore, the concentration of added sodium sulfate played a significant role with respect to the swelling properties of MPPA-modified hydrogels. These smart materials may be of interest in the biomedical field as well as in other applications.